Process of melting, purification, and recovery of metals



Patented Mar. 28, 1939 PROCESS OF MELTING, PURIFICATION, AND RECOVERY OFMETALS George H. Goldsmith, Pawtucket, 1L1.

No Drawing.

Application August 10, 1936 Serial No. 95,175

20 Claims. 7

This application is a continuation in part of my co-pending application,Serial No. 4,557, filed February 1, 1935. The invention relates to aprocess of refining mixtures of miscellaneous ferrous and non-ferrousmetals and alloys, and

particularly those mixtures containing metallic iron and predominatelycomposed of brass and bronze alloys having inclusions of aluminum,sil-

icon and iron present therein; and has for one of its objects theremoval or controlling of those constituents thereof whose presencetherein renders the brasses and bronzes unsuited for producing good,sound castings.

Another object of the invention is to provide a process of treating suchheterogeneous mixtures of ferrous and non-ferrous materials whereby thedifferent undesirable elements, such as iron, silicon and eluminumcommonly found as inclusions among and in the non-ferrous scrap alloysare not rapidly removed from the mixture but whereof a delayed oxidationof these impurities is efiectedto cause them to be continued indiminishing quantities therein and converted into useful cooperants inproportions and relationships which beneficially influence thecomposition and mechanical properties of the final non-ferrous casting,and without serious loss of. any ofthe essential metal constituents ofthe non-ferrous alloys. I

Another object of the invention is to provide a method of meltingmixtures of predominantly brass or bronze alloys whereby the productionof melting temperatures in the same is effected by an indirect heatingmedium, and in which 35 volatilization of the tin, lead and zincconstituents of the brass or bronze will be avoided; and particularly toreduce the use of direct melting apparatus utilizing localized meltingzones, such as the stack typeof furnace used with direct fuel melting,or an electric furnace of the arctype, whereby melting of the metalresults by an extended exposure of the mixture to high tem peratures,although my process repeatedly makes use of direct melting methods,under some cir- 4 45 cumstances.

Another object of the invention is to provide a method of meltingpredominantly brass and bronze scrap material in such a manner that anyinclusions of free iron therewith are separated and recovered at thetime of melting and withdrawal of the recovered brasses and bronzesinstead of previous thereto.

Another object of the invention is to control the dissolved ironinclusions in non-ferrous metal 55 mixtures so thatit cannot formsilicates or carbide compounds which are detrimental to the brass andbronze castings, which otherwise are rarely wholly free of iron -undergood foundry practices. 7

Another object of the invention is to restore 5 the cementite orcrystaibinding action which characterizes brass and bronze alloys andwhich may have been destroyed by the presence or use of aluminum as anundesired constituent of the alloy materials from which the brass and 0bronze alloys are composei With these and other objects in view myinvention resides in the steps of the process herein described andcovered by the appended claims, and it may best bedescribed inconnection with 15 the actual procedure to be performed in a particularapplication and adaptation of the invention in use; and the following isa more detailed description of such application and adaptation forillustrative purposes: 2o

Heretofore in the preparation for melting and casting of miscellaneousferrous and non-ferrous mixtures consisting mainly of scrap brasses andbronzes, it has been customary to give considerable attention to thediligent removal and separation of all metalliciron parts such asscrews; nuts or the like, from such scrap previous to melting, by thebest mechanical or physicaldevices which have been available, andthereafter to fuse or melt the scrap at high melting zone 30temperatures under conditions of. directly applied heat. Furthermore,the presence of unwanted inclusions of iron. carbide, slag-iron, andaluminum in crystal-upsetting form, has been considered highlydetrimental as destroying what may here be referred to as the "cementiaction in the final castings of the non-ferrous base metal. V Theabove-mentioned undesirable" inclusions existing within the scrap metalmixture comprise 40 those which are the normal and persistent impuritiesof non-ferrous alloys and compounds and even when present in extremelysmall amounts, it is found that they render the alloys not properlyuseable for making sound castings since they exert a profound influenceon the physical properties and structure of the final casting, renderingit relatively brittle and with a crystalline structure that isdemonstrably weak, under fracture tests. Furthermore, the effect of;

the presence even'of small amounts greater than a-trace of aluminum oraluminum compounds often is suflicient to cause these mrious upsets ofthe crystalline structure of the cast material, besides producingdetrimental upsets of the cementite thereof. By the term "cementite isspecifically meant the functional effect or action in the metals of thenon-ferrous group, of the oxids of copper, tin, lead and zinc presenttherein as crystal binding compounds in solution therewith. Aluminum inthe brasses and bronzes re-,

sults in the presence of uncemented crystals that render the castproducts porous and leaky unless enough aluminum is used to constituteby itself an alloyed ingredient.

However, such prior efiorts have not proved successful in convertingbrass and bronze alloys, of substantial purity with re-use of incidentalfoundry scrap in making safe castings so that the foundries have beendriven into the use of pure ingot metal extensively, to avoid thereentry of these unwanted inclusions of free iron, silicon and aluminum,with their various combinations, into the regular brasses and bronzes ofevery day use.

Thus, many foundries return their waste materials, such as gates, sprewsand risers, and all machine shop brass scrap back to the metalsupplyhouses, in order to avoid re-use of this metal waste in the final meltwith the attendant danger of iron-carbide, slag-iron, and unwantedaluminum inclusions, among the final castings.

According to my present invention, I do notattempt to physically removeor separate any of the iron present among the non-ferrous metal prior tothe melting of the scrap when the iron content is ten percent or less;nor do I consider the presence of iron, silicon and aluminum at alldetrimental in small amounts up to one percent by weight of the total inaluminum, but conserve the-same for use in my process and carry themalong to some extent with the brasses or bronzes; and in fact, ifaluminum is not present insmall proportion I add it in sufiicientamounts to perform certain rectifying or refining operations in myprocess; usually to the amount of from one to.flve one hundredths of onepercent of the whole.

If aluminum exists in the scrap metal in amounts in excess of onepercent I ordinarily add more scrap brass and bronze known to be free ofv aluminum, but do not ordinarily pick it out from the scrap, and anapproximate amount of one. percent may vary greatly without harm. Scrapestablish; and I utilize these amnities with very.

greatly increased capacity for their advantageous application inattaining my objectives, mainly by avoiding high melting zonetemperatures and by deferred oxidation.

Another feature of the invention resides in my and application of addedmetallic iron in circumstances where it has previously been diligentlyexcluded in this field of brass and bronze conversion.

To this end, my process makes use of the higher aluminum and siliconwith very short exposure to high temperatures to enable saving tin, leadandzinc.

A sound reason for using iron instead of straight copper, as a. bathmetal, is because iron is cheap and may be re-used over and over, whilecopper costs several times as much and requires virgin tin, lead, andzinc'to rectify for bronze, brass, etc.

As a further feature of my invention, I propose to carryout theoperation of controlling the undesired constituents of the scrapmixture, instead of removing them at once, and the final production ofcastings from such treated product, by two separate operating steps,each of which is applicable within a foundry wherein refining of thescrap and casting of the recovered brass and bronze alloys may beconducted on a large-scale tonnage basis, in which the first step of myprocess consists in heating to a red hot semi-fluid, or molten state, amixture of ferrous and nonferrous metals in an electric furnace underconditions wherebythe reduction and control of the undesiredconstituents of the mixture may be effected, and melting temperaturesproduced gated and recovered from the combination of iron-group materialand the original metal mixture. The brass and bronze mass is thereafterallowed to solidify into ingot or pig form after adding metallicaluminum, removing the surface mass of iron bath metal, slag and oxideinclusions, and by making additions of rectifying materials ormixturessuch as tin, lead, zinc antimony, phosphorous, nickel,manganese, silicon,

etc., to make the desired brass or bronze alloy product for castingpurposes with deficiencies supplied based on the brass or bronzeconstitution of the original mixture and the copper or other metalsupplied fronr the iron-bath metal components.

. The solidified ingot or cast mass resulting from the abovetreatmentwill have a content of the undesirable constituents of the originalmetal mixture, vlz., iron, silicon and aluminum, in incompletelyoxidized form and in amounts up to saturation, since any excessthereabove has been drossed oif prior to ingotting and by segregationand separation of the iron portion of the fiuid ferrous melting vehicleadded to melt the mixture, which iron mass when recovered holds aconsiderable part of the undesirable inclusions, as previously stated,together with any released unmelted metallic iron; and any excess ofoxides of the brasses and bronzes as maybe released from the meltedmixture are removed by skimming. This intermediate ingot product thusformed is not fit for general direct casting purposes instead ofingotting due principally to the upset in the cementite action of ingotmetal destroyed or partially inhibited in its crystalbinding functioncaused by the high percentage of included aluminum which is readilyshown by fracture. Also, the amounts of the inclusions of aluminum andsilicon in combined or in metallic forms within this intermediate ingotare from a hundred to a thousand times the conventional amounts inso-called pure ingot metal,

Y whole metal.

The second operating step of my process comprises remelting the ingot orcast solidified product produced by the first step treatment, tocomplete the oxidation of the silicon and aluminum and re-establish thenormal and usual copper, tin, lead and zinc oxidecementite function anddesirable crystalline structure of cast brass and bronze end-product byrestoring'these oxids to saturate solution; and the following is a moredetailed description of the invention as above set forth:

In the practice of the invention for scrap conversion I carry out thefirst operating step of my process and accomplish rapid fusion or melting of the predominately non-ferrous metal scrap, preferably byemploying as the final melting agency therefor whatv I call hereafter abath metal, which is a high temperature melting metal, preferably mostlymetallic iron, and I utilize this bath metal only under circumstancesthat favor its use in which it is applied in red hot, molten, or plasticform directly to contact therewith, instead of direct fuel melting orcrucible melting by localized heating. Furthermore, I find the principalability to make use of'the bath metal arises from its inherent meltingtemperature which is much higher than that of ordinary brasses orbronzes, and by reason of this temperature characteristic and throughcontrol thereof and by mixture with metal additions I accomplish thecooperation of iron in the manner brought about in the carrying out ofmy process.

Hereafter I intend to designate and referto the mixture of ferrous andnon-ferrous alloys and metals to be processed by the term cruciblemetals, whether the usual crucible is actually the receptacle or meltingvessel used for holding the metals during the process or not; and I alsohave confined my process to the application of base metals andcommercial alloys only, and have not applied it to precious metals dueto the prohibitive expense of experimenting with them. This scrapmixture or crucible metal illustrated is composed mainly of the commonor standard brasses or bronzes contaminated with iron parts; though theprocess applies in converting pure ingot metal as well.

I usually apply the bath metal in either plastic or molten form tosurround or cover the crucible metal for accomplishing the thermaltransfer mentioned, but it is to be understood, however, that I maycarry this application of the bath metal tothe crucible metal to thepoint of accomplishing either plasticity, fusion, or volatilizationthereof; the latter result, however, being for extraneous applicationsonly; and I may apply merely very hot but unmolten bath metal for thispurpose.

In practice, I preferably add the predominately non-ferrous cruciblemetals into the bath metal after the latter has been melted in anelectric furnace, but I may also apply the entire bath metal mixturemolten or the iron portion molten, or very hot, directly to the cruciblemetal within a conventional melting crucible, receptacle or ladle, foraccomplishing any or all of the-objects of the invention. Also, I mayapply the bath metal to the crucible metals which have been preheated ormade plastic or molten in the crucible before applyingthe bath metal,sometimes with continued application of heat to the stiffened ironsegregated to the top of molten crucible metal; and instead of molteniron or copper-iron I may apply red hot pellets or washers to cover thecrucible metal until plastic or fused.

As a specific illustration of one manner of practicing my invention, anappropriate charge of the bath metal, mainly iron, which may or may notbe mixed with a lesser'content of copper or other metal constituent ofthe brass and bronze alloy scrap, is loaded into an electrical meltingfurnace of the oscillating type and brought to a plastic or moltencondition. The furnace employed may comprise a conventional corelessinduction furnace of the type well-known in the art in whichenergization is attained by high frequency power and melting of thecharge is caused by, the generation of heat therein due to theelectrical resistance of the charge to induced current and thetransformer effect while functioning a secondary coil; or it may beheated with a carbon arc flame type of electric furnace.

The composition of this bath metal which is to be applied to thecrucible metals for the primary purpose of direct thermal transferthereto preferably should be one composed predominately of pure metalliciron, preferably refined by re-use for this purpose, with as large aproportion of copper sometimes added when it is melted, as

may be usefully included in the desired alloyconstituents of the finalcrucible metal, and with such'amounts of silica and alumina as may bepresent in both the iron and in the crucible metals that are to be addedlater, which materials are gradually eliminated by repeated oxidation,so that the iron portion of the bath metal that is not burned up withaluminum may be separated, re-melted and re-applied with increasingpurity for treating subsequent mixtures. .The carbon content of theiron, however, plays an unimportant part as long as-aluminum continuesto be present and also diminishes by release as, CO2 with use and re-useof the iron for this purpose. One typical example of a bath metalmixture suitable for the purposes of the invention comprises a mixturewith preferably not less than forty percent of copper, and the remaindernot less than'fifty percent of iron, and iron-group inclusions.

I then melt the contents of the furnace during which operation I skimoff the surface oxides, ferrous, alumina, silica, slag, etc., and Iregulate the temperature of the furnace according to the meltingtemperature subsequently desired for metals added later to the bathmetal.- As a rule, controlled temperatures are obtained more byselecting melting temperatures of metal mixtures of the bath metal thanby furnace regulation, although both means are used, as well aspre-heating or even melting of the crucible metals. The most commonmelting and pouring temperature of the bath metal is approximately 2000to 2200 F. It is fesible to employ melting temperatures of copper-ironbath mixtures of 1900 to 2500 F. applied to fuse crucible metals, whilehot pellets of steel or iron may be used at 2200 apinto the ferrous bathmetal already molten or semi-fluid, and if necessary I may raise thetemperature of the furnace again to prevent the bath metal fromstiffening too rapidly before fusion of the crucible metal has beenaccomplished, al-

though I may permit the fusion of the latter to go only as far asplasticity, or further to the point of volatilization, the latter onlyforextraneous applications of the metallic gases; but as far as possibleI accomplish the processing, within the. furnace, by reason of directthermal transfer from the bath to the crucible metal entirely, withoutdirect exposure to high melting zone temperatures. I preferably continuethe oscillation of the furnace during the fusion of the entire mass ofmetals, excepting during the application of the crucible to the bathmetal. During this operation the copper component of the iron bathmixture is transferred by confluence to the brass and bronze portions ofthe melt. Hence, the copper portion of the bath mixture is kept hotterthan it could be normally raised in temperature during melting amongnon-ferrous alloys. Also, the iron portion of the bath metal is broughtto a lower temperature than would normally melt iron alone so thatcombustion of aluminum with; in a controllable extent is possible tocause 9. raising of the temperature of the whole mixture while burningout aluminum and silicon inclusions' of the brasses and bronzes and thusaccomplish fusion of the non-ferrous portionof the scrap or cruciblemetal so rapidly that oxygen is largely occluded by the molten metal,while the burning aluminum acts as a. reducing agent resilicon andaluminum and carbon, as may readily be removed alone.

If any iron remains in the furnace, I prefer to allow it to stiffen withaccompanying imprisonment of free iron inclusions, and also aluminum andsilicon, all captured from the crucible metals as inclusions unwantedtherein, and I preferably 'remove the iron while still very hot andbefore it sticks to the furnace walls and before it has burned out itsalumina and silica contents completely, the latter being preferablyremoved from the bath metal by re-melting of the iron thereof beforere-application of the iron thus recovered as bath metal for subsequentuse in treating future scrap metals in the crucible.

I may add to the molten brass and bronze metals thus separated metallicaluminum prefer-. .ably to the amount of not more than one onehundredthof one percent of the total non-fer rous mixture content if the originalaluminum content of the crucible non-ferrous metal is insufficient, thelatter aluminum being present during fusing of the scrap and insuflicient quantity to be diffused throughout the charge, 1. e., asubstantial dispersion throughout both the brass and iron-group portionssegregated from the original scrap mixture. This diffusion of thealuminum among the entire mixture of metals results in intimatedisplacement of the oxides in solution to reduce them to a substantialdegree from the normal saturating point, releasing the oxids as dross tobe skimmed off the molten metal; it also serves to remove silicon fromthe brasses. bronze and'iron of the mixture, and from the copper addedthereto with the bath metal. so that silica and alumina form and rise tomeet the iron. The aluminum thus acts to prevent combining of the ironand the silicon, and

' in addition, it has a combining power sufiicient to prevent recurrenceof slag-iron and iron carbide form'ation's in the intermediatenon-ferrous ingot and with metal melted therewith.

In view of the greater afllnity which the aluminum has for iron thandoes either the silicon or the carbon, the iron will therefore beattracted away from the silicon or carbon and caused to unite with thealuminum. After the iron-alumiducerof the oxidecf a metal I have foundthat when this aluminum is added in accordance with the presentinvention, it permeates the entire furnace charge as a gas and. therebyserves to displace the'normal oxides of the copper, lead, tin and zincconstituents of the scrap metal, thus interfering with. or 'destroyingthe normal cementite' action in the non-ferrous metal. Consequently if acasting were subsequently made from such a material after the aluminumhad permeated the entire melt, the destroyed action of the metal oxidewould cause the-final casting to be porous and to leak, which is thegreatly dreaded condition by all foundry men who have learned by pastexperience to abhor the presence of aluminum in the brasses and bronzesbecause of this action. t v

I next pour or draw off from the furnace the remaining metal composed ofthe original crucible metal and any non-ferrous ingredients eithertransferred from the original bath metal mixture to the crucible metal,or, of those components with metals such as tin, lead, zinc or antimony,or mixtures thereof, added for rectification just before or directlyafter the iron portion of the bath mixture was removed from the othermetals, to enable the desired alloy content of the crucible metal. Ithen put this new crucible metal, partially processed and preferablysolidified, into one or more receptacles adapted for receiving,

ing molten non-ferr6Ts metals, and, if necessary, I may add any portionor one of my intermediate ingots heretofore described from apreviousmelt to any or all'of the receptacles mentioned, kepthot enough so thatits metal contents may disperse the ingredients of the intermediateingot metal so added, throughout the mixture.

But I preferably add the intermediate ingot to the crucible metals inthe furnace along with the bath metal, so that it may be melted by thebath metal when the crucible metal'is melted thereby.

If I add phosphorous to the crucible metal I preferably do it afterpouringthe latter from the furnace, and, if possible, in the absence ofiron, unless the latter is added as an alloy to the crucible metals toremain therewith, or unless resolved iron is known to be excessive.

It has been observed that the prior use of heating, measuring,dispensing, shaping, or holdphosphorous in such melts results in much ofthe iron dissolving among the brasses and bronzes, and this practicehascaused a considerable part of the previous persistence of iron amongthese iron segregated from the crucible metals melted by the bath metal,and then applying the phosphorous along with other alloying constituentsdesired. In such an instance, it will be found that while the presenceof phosphorous among with aluminunn l I ,then either discard part or theiron first poured out of the furnace, or I recover it entirely forre-application; or I return part of the bath metal iron to re-meltingand re-application, and

apply the'remainder for other purposes, such as inclusions in anend-product ingot, either wholly ferrous, or partly ferrous; the sameiron portion of .the bath metal recovered being purified by reason ofits use as a bath metal after repeated returning to re-m'elting andre-application for this purpose.- 4 j I then dispense the crucible metalfrom the receptacle, and either cast'directly or ingot the metal, 7preferably completely separated from its ferrous content; and for adispensing receptacle I prefer the tea kettle variety of ladle to enabledrawing off the non-ferrous metal from below the stiffening ferrousportion. of the bath metal, if anyremains.

In consequence of the use ,and application of the bath metal in thepresence of aluminum I both produce and utilize a more or less pure ironas an intermediate product which has many uses for extraneousapplication, although I may separate and discard all or part of the ironportion, after it has been applied to the crucible metal, or before suchapplication, if the free iron inclusions captured from the cruciblemetals are excessive in amounts for use wholly returned to the bathmetal when it is remelted; and I may employ a separate melting means forthe ferrous portion of the bath metal using aluminum for improving itscondition by reducing silicon thereof.

I preferably produce the. intermediate ingot previously described, whenI utilize the bath metal described, andwhen silicon and alumi- .f numare both present, they naturally combine and in that form are easilyburned out ,by way of transfer "to the bath metal, or "by way oftransfer into the crucible metal,' which is subjected to the secondmelting when the ingot metal intermediate is melted for casting, and toelimination of silicon and-aluminum in conse It' will of course beunderstood that other equally feasible methods may be utilized toquickly melt the scrap material in order that the lead, tin and zincconstituents thereof, which fuse at a moderate temperature, will not beconsumed by combustion or be volatilized. For example, it is feasible toload the scrap into a suitable receiving vessel or crucible and then toaccomplish melting of this scrap by pouring hot or molten iron over it.In this instance a pro-heated crucible is sometimes preferred. By usingmolten iron in accordance with this invention it quickly melts brassesand bronzes which have a lower melting temperature than iron, and thequantity which I use is suchvthat it gives up so much of its heat thatthe ferrous bath metal begins to stilfen as it congeals in this form itrises upon the molten brass or bronze and is quickly removed either byraking it out of the potor by drawing of! the brass or bronze beneathit, as by means of the tea kettle dispensing ladle heretofore mentioned.In this way, the iron used for melting the brass or bronze is againquickly separated and recovered from the melt since all of the free ironin the scrap rises to the top where it clings to the congealed iron.This operation practically removes substantially all of the free ironfrom the mixture and so quickly melts the brass or bronze crucible metalthat practically none of the tin, lead and zinc present is consumed.Thus,,the

solidified melt will be practically free from unwanted inclusions of anykind.

In accordance with the first stage of my process it will be found thatthe aluminum oxide in quantities greater than saturation and tempera--molten brass or bronze melt and is skimmed off.

However, the, intermediate ingot contains the aluminum in both metallicand oxidized form but in which the cementite action of the zinc, tin,copper and lead oxides of the solidified mass is destroyed. This"cementite action is re-formed by restoration of normal oxids insolution and the crucible metal entirely purged of aluminum which isburned out by subjection to the temperature of re-melting.

By means of thepresent method of re-melting and casting the intermediateingot product, a greater bulk of tin, lead and zinc is kept from beingvolatilized by reason of their occlusion while fusing under theiron-copper mixture, than the ordinary time and temperature meltingconditions in usepermit. For instance, an ironcopper mixture at 2000 F.will, upon being poured .over a -crucible content of the brass or bronzescrap, give a molten crucible mixture in melting range from prasticityto high fluidity the respective temperatures of which being from about800 to 950 F. during plasticity of the type desired, and from about 950to 1100 F. if barely fused. The latent heat of fusion of metals meltedby the bath metal is an important factor controlling the ultimatetemperature of the crucible metal melted'wlth it. For this reason. noteven relatively small amounts of cold crucible metals approach anywherenear the temperature of the bath metal when melted thereby.

In accordance with this invention, I have provided an improved processfor manufacturing brass and bronzecastings from impure metal scrap whicheliminates much of the hand labor re-grouping them according to whatamounts of destructive oxidation they will stand from past methods ofpurifying these metals.

Moreover, by employing this method I accomplish direct thermal transferfrom the bath metal to cause fusion or melting of the crucible 'metalscrap or ingot, during which operation there results occlusion of oxygenand control of oxidation of the aluminum, silicon and iron during fusionor melting of the crucible metal; dispersion of aluminum and siliconaccompanied by exchange of both between the crucible and the bathmetals; dispersion of other concentrations such as nickel; release offree iron from the crucible metals and capture therefrom by the bathmetal iron portion; avoidance of destructive melting temperatures forconserving tin, zinc and lead constituents of the brasses and bronzes;and a rapid and economical melting operation as to off-set any departurefrom standard foundry procedure occasioned by the use of two melts inthe foundry; and finally, the ability to use the preferred electricalmelting method more economically in melting a predominantly ferrous,instead of a non-ferrous mixture, meaning its use in melting the bathmetal.

It will now be apparent that by my process I am able to utilize thepresence of aluminum and silicon among the brasses' and bronzes not onlyby reason of the cooperation between the former substances. and iron,but also by reason of providing for two outlets and one by-pass ofalumina and silica, which are described as follows: first,

an outlet by way ,of the bath metal and by remelting the latter; second,a by-pass by wayof the intermediate ingot instead of direct casting;third, an outlet by way of the re-melting of the intermediate ingot withcompletion of the oxidation through non-ferrous channels.

It is to be understood that the use of the intermediate aluminum-bearingingot does not necessarily accompany the presence of free iron, but itrepresents primarily a device for preventing the combination of any ironthat may later be admitted to the brass or bronze from combining witheither silicon or carbon. Also, I may utilize the iron bath metal foraccomplishing rapid fusion of pure brass or bronze with controlledoxidation and salvaging of tin, zinc, and

lead, and then pour into direct end-products castings instead ofingotting; or I may then add aluminum and ingot the intermediate productthen made.

In the event, however, that the crucible metal and the purified bathmetal iron, and any other metal constituent of the bath metal are sonearly free of aluminum andsilicon as to be able to ingot or cast forall general foundry purposes either the ingot or the castings becomeend-products, suitable for use as pure ingot metal would be suitable tocast or ingot, in conventional practices, or if the silicon content ofthe metals is adapted for end-product use, with the aluminum contentnegligible, or usefully applied, then the metal either cast or ingottedbecomes an endproduct.

If I re-melt the intermediate ingot non-ferrous metal, it will bemodified thereby by the inci* dental oxidation preferably accompanyingthe use of either direct-fuel or the electrical melting methods, and itwill be rendered practically free of alumina and silica when re-meltedmainly for purpose of improving its own metal content thereby; the samealumina and silica contents being not over one-half of one percent inthe intermediate ingot before re-melting; but if the said alumina andsilica contents are in excess of five-tenths of one percent of theintermediate ingot metal content, then the metal of the intermediate ispreferably melted along with other metals for the purposes of preventingslag-iron and iron-carbide inclusions, and dispersion of otherinclusions within the intermediate ingot among the end-products.

By the term aluminum bearing dross as employed in the specification andclaims, I mean in some instances to describe the insoluble compounds ofaluminum metal 'with the component metals oxidswhich tend to rise and tobe lost by skimming the molten metals and hence are of a drossycharacter and, in other instances, I intend the term to designate thissame compound as partially oxidised aluminum in combination withcomponent metal oxids of the alloyed brasses or bronzes; It is to beunderstood that the phase of the process described herein which dependsupon the action of aluminum combined with the oxids mentioned isaccomplished both by the initial action of aluminum in throwing theoxids out of solution and by the ability of the aluminum bearing drossto give up its aluminum and combine with iron, silicon, etc.; and thatthis process could not be carried out without the generation andapplication of the aluminum bearing dross against the reactions ofcarbon, silicon and iron in remelted metals; nor could it be carried outwithout conserving within the melted brass as much of the insolublealuminum bearing dross as may be accomplished by the melting methodsdescribed and by uses of the temperatures of the molten metals describedand .to rise.

Having thus described my invention, what I claim as new and desire tosecure by Letters Patent is: v

1. The process of treating mixtures of predominately non-ferrous metalsfor preventing combinations of slag-iron and ironcarbide among brassesor bronzes, comprising the steps of melting a mixture of mainly brass orbronze in the presence of aluminum in an amount that its content be notmore than one one-hundredth of one percent of the total non-ferrousmixture content to be diffused throughout the mixture, casting themixture into ingot form with demonstrable upset of the cementite of thecrystalline structure upon fracture to render it unfit for themanufacture of pressure-subjected castings, and thereafter melting theintermediate metal ingot to thereby demonstrably restore the cementitefunction and converting the intermediate ingot into end-product form,both of said products being immune to slag-iron and iron-carbideformations by reason of the burning out of silicon and release of ironfrom silicon and carbon combinations in the presence of minutequantities of aluminum, said brass or bronze alloy end-product.

being freed of aluminum and iron to the extent metal in a quantity thatits content be not more than one one-hundredth of one percent of thetotal non-ferrous mixture content to cause an upset in the cementitefunction of the metal demonstrable upon fracture, casting the treatedmetal into ingot form, and thereafter melting the treated metal alongwith added brass or bronze to thereby restore the cementite function ofthe brass or bronze constituents and prevent combinations of iron withsilicon and carbon by reason of the higher combining affinity of ironand aluminum over the afiinity of iron toward silicon and carbon.

' brass or-bronze and having an aluminum content, not essentially aworking component of the alloy and of less than one one-hundredth of onepercent thereof to cause definite temporary prevention of the normalfunction of the cementite of the metal to thereby render the metal ofthe ingot unsuitable for pressure subjected castings instead of'ingotting, said ingot metal being immune to the formation of slag-ironand ironcarbide combinations until the aluminum content is burned out bysubsequent melting, and in which the said interruption of the cementitefunction is restored by the subsequent melting of the ingot to renderthe intermediate ingot metal suitable for all casting purposes of thealloy as an end-product.

5. An intermediate ingot composed mainly of brass or bronze and havingan aluminum content, not a working component of the alloy, and a of lessthan one onehundredth of one percent thereof to cause a pronounced upsetin the crystalline structure of the metal of the ingot and to bedispersed among additional metal melted therewith with sufficientcombining capacity to prevent slag-iron and iron-carbide combinationsamong the entire mixture of the ingot and aded metal, said aluminumcontent being sufficiently dilute and dispersed to enable itselimination by oxidation duringthe subsequent melting of theintermediatemetal and added metal with restoration of the cementite function of theentire mixture.

6. The process of removing free iron parts from heterogeneous metalmixtures of mainly brass or bronze which comprises the steps of meltingto at least a semi-fluid state the entire mixture, except the ironparts, removing by raking or screening most of the unmelted ironportions, and. thereafter recovering the' brass' or bronze from theremaining iron parts by segregation of and removal of the iron particlesremaining with the use of added iron in the molten state applied to thetop of the moltenbrass or bronze.

7. The process of purifying predominantly non-ferrous metal mixturesconsisting mainly of brasses or bronzes contaminated with inclusions ofiron, silicon and aluminum which comprises providing a high aluminumcontent, heating the brass or bronze to a fluid condition in thepresence of said aluminum content with the aluminum in sufficientquantity to effect combination of the aluminum with substantially allthe iron and the silicon existing within the metal mixture so as toprevent combinations of iron), silicon and carbon.

8. The method of treating brass 0'! bronze alloy metals which comprisesrapidly melting the brass or bronze by direct thermal contact with amolten metal having a higher melting temperature than that of standardbrasses and bronzes to render them fluid and to prevent removaltherefrom by oxidation of the major constituents of the brass or bronzealloys.

9. The process of melting, refining and recovering brass or bronzemixtures from miscellaneous scrap containing ten percent or less ofdissolved and free iron parts, which comprises the steps of firstmelting the entire mixture excepting the of. aluminum bearing dross thatis also insoluble in the molten brass or bronze, and then casting thetreated metal into end products of demonstrably normal crystalline metalstructure and 'having a dissolved iron content reduced from the averageof the initial scrap mixture and having a demonstrable freedom from thepresence of either iron .carbide or iron silicon combinations.

10. The process of melting, refining and recovering brass or bronzeresultants from miscellaneous mixtures' of predominantly brass or bronzescrap mixtures containing ten percent of dissolved and free iron withmore or less sili con and other metals of no significance in thisprocess, which comprises the steps of first melting the entire mixtureexcepting free iron not fusible under the conditions with a mixture ofcopper and iron in about equal parts and applied at a temperaturebetween 2000 F. and 3000 F. for direct thermal transfer 'therefrom' tothe treated metal with the copper ,content of the melting copper-ironmixture added tothe brass or' bronze resultant by confluence, in thepresence of five percent of aluminum bearing dross, then skimming offthe excess of the said dross along with the floating free iron parts andassociated oxids and burned metallic compounds, alumina and silica, andthen pouring into end products castings, the temperature of the treatedmetal at pouring being between 1800 and 2300 F.

11.'The process of refining brass or bronze metals with reduction andcontrol of deleterious dissolved iron, silicon and carbin enteringvtherehaving a maximum content or aluminum bearing dross conserved forapplication of the, aluminum content thereof against reactions of thesaid iron and silicon contents withprevention of combination of the saidiron and carbon and prevention of upset in the metal structure of boththe said 1 intermediate ingot and-metal melted along therewith for theaforementioned purposes, then melting the final mixture of saidintermediate ingot along with the added metal, and then pouring the newmixture into end products-castings.

12. An intermediate ingot for use in a process for melting and refiningbrass or bronze metals whereby the said brass or bronze may be pro-"tected from the formation 01' iron-silicate and iron-carbidecombinations during melting operations; said ingot containing a majorcontent of aluminum bearing dross and a minor content of brass or bronzemetal as a binder for the said active purifying agent aluminum bearingdross. 13. An intermediate ingot containing at least fifty percent ofaluminum bearing dross bound with a content of brass or bronze as lowastwenty percent, wherein said brass or bronze content acts as a binderfor a maximum of aluminum bearing dross for the purpose of obtaining thegreatest possible active andharmless combining strength of the reactionsof its aluminum content against silicon and iron ingredients amongst thebrasses or bronzes melted along with the said ingot for purposes of thisprocess.

14. An intermediate ingot composed predominately of brass or bronze andhaving an aluminum bearing dross content of one percent or lessassociated with an equal amount of unimportant oxids and dissolved iron,silica and alumina, the said ingot being composed for the purpose ofremelting and thereby refining the said content of brass or bronze.

15. An intermediate product ingot consisting of mainly pure metalliciron mixed with a minor quantity of aluminum bearing dross acquired byreason of use of the iron which has contacted plastic brass or bronze inthe presence of generation of aluminum bearing dross under temperatureconditions that favored retention of the said dross instead of completeburning" out of the aluminum.

16. .An intermediate product ingot consisting of mainly a mixture ofcopper and iron in even proportions and a minor content of aluminumbearing dross acquired by reason of the use of the copper-ironmixture-under temperature conditions that favored retention of the saiddross instead of complete burning out of the aluminum content.

1'7. The process of converting mixtures composed predominately of pureingot metal brass or bronze alloys andv containing an aluminum bearingintermediate ingot along with the pure ingot metal of substantially thesame alloy to produce a non-ferrous end-product and a ferrousend-product, comprising the steps of first heating to at least asemi-fluid state a quantity of bath metal consisting of a mixture ofmainly pure aromas metallic-iron and of copper in about equalproportions, said copper being intended for final transfer to the brassor bronze resultant mixture finally recovered and being used for thepurpose of lowering the melting point of the bath metal, thenmaintaining the said iron-copper mixture in a heated condition andadding to the bath metal mixtureas much brass or bronze mixture as willreadily become-fluid as a consequence of direct thermal transfer theretofrom the bath metal, then awaiting fluidity and action of the ironportion upon the-entire mixture to which the copper portion isv added byconfluence then separating the iron portion of the bath metal along withinclusions of oxids and metallic ingredients added to the iron duringthe treatment by segregation of the iron from the non-ferrous mixture,then recovering the segregated iron portion with its inclusionsmentioned as a ferrous intermediate product for partial re-use as asubsequent component of the iron-copper mixture, then casting oringotting the brass or bronze 'resultant mass remaining and recovered asan bearing dross sum cient to react upon dissolved ,jthe said brass orbronze while both the ingot and the brass or bronze are subjected to atemperature between 1500 Rand 3500 F.

19. An end-product ingot composed of a mixture of mainly pure iron andof copper containing ten percent or less of aluminum bearing dross, thesaid ingot being composed for the purpose of heating and applying tonon-ferrous metal mixtures of mainly brass or bronze compositions fortreatment thereof.

20. In a process of converting brass or bronze involving melting or heattreatment, the method of refining the brass or bronze which consists inperforming the process with or after introduction of aluminum bearingdross into the brass or bronze, the said dross being composed mainly ofloosely attached atoms of aluminum combined with the oxides ofnon-ferrous metals such as brass alloy constituents, as opposed to inertalumina or silica, the said aluminum atom being detachable for reactionagainst silicon and iron under temperature conditions adapted to favorthis reaction of aluminum bearing dross against silicon and iron.

